In a longitudinal study of the offspring of affectively ill and well parents, we have addressed the following questions: What are the long term sequelae in children of depressed mothers? What are the diverse developmental courses? What are mechanisms accounting for the emergence and maintenance of psychiatric disorders in the offspring? Of special interest is the development of major mood disorders in the offspring. Development and its correlates in ill and well families have been followed from children's early years through adolescence. Integrative longitudinal analyses provide findings on (1) distinct developmental problem patterns for offspring of unipolar and bipolar mothers, (2) differential precursor patterns for children with outcomes of mood disorder and children with other problematic outcomes., (3) distinct and diverse mechanisms linking maternal depression with psychiatric problems of offspring, and (4) the interactive impact of maternal depression and its correlated behavioral environments on children's functioning.